NOTES ON THE TECHNIQUE OF THE OTTER FIELD SURVEY

Data (2083 sites visited) collected during the otter Lutra lutra (Linn aeus, 1758) survey of Poland in 1991-1994 were used to evaluate some o f the factors affecting the efficiency of the technique. The success i n detecting otter signs was found to be significantly affected by the presence of ''spraintable'' bridges and other potential sprainting sit es on the banks. Decreased efficiency of the technique was noted in sp ecific habitats, eg large rivers, canals surrounded by open fields or meadows, and any aquatic habitats with few potential sprainting sites on the banks. It is suggested that modifications: spot checks at addit ional bridges and extended searches of river banks, could be used to i mprove the reliability of the survey in areas with low numbers of otte r signs.